(1) Field of the Invention
This invention relates to combination locks having an automatic scrambling mechanism whereby the operating mechanism of the lock is scrambled upon closing of the lock to automatically upset the unlocking alignment of the operating mechanism thereby eliminating the need of manual scrambling by a person operating the lock.
(2) Description of the Prior Art
A persistent problem in the combination lock art has been the danger of the lock being opened by an unauthorized person if the unlocking mechanism has not been completely scrambled or upset. The problem arises when an authorized person dials the correct combination, opens the lock and then closes the lock without disturbing the final setting. Since the final setting of the lock has placed the lock mechanism in proper alignment to accomplish the unlocking movement, it is possible in many locks for an unauthorized person to open the lock.
U.S. Pat. No. 3,481,167 to Elwood M. Barner, discloses a scrambling mechanism for a combination lock. This patent discloses a rotatable tumbler combination lock having a resiliently mounted cam which interacts with a cam surface on the dog lever to disengage the dog mechanism upon movement of the bolt to the unlocked position and return the dog mechanism to the locked position. A spring normally urges the dog mechanism towards the position of engagement so that engagement for unlocking is accomplished when the tumblers and the driving disc are properly aligned. Movement of the bolt plate toward the unlocked position removes the spring bias from the dog mechanism and the resiliently mounted cam disengages the dog mechanism for return to the locked position when the dial is released.
U.S. Pat. No. 3,447,348 also discloses a scrambling mechanism for a combination lock. This patent discloses an upset mechanism which includes a resilient spring which is mounted to the casing of the lock and which engages detents in the tumblers of the lock to scramble the lock. A disadvantage with this type of scrambler is that it requires an elongated spring which is subject to wear.
It is an object of the present invention to provide a simplified scrambler mechanism for a conventional combination lock. It is also an object of the present invention to provide a scrambler mechanism which is subject to less wear than is known in the prior art.